//属性嵌套
/* div{
    height: 100px;
    font: { //空格
    size: 20px;
    weight: 300;
}
} */
//占位符选择器
.button%base{
    height: 100px;
    font: {
        //空格
        size: 20px;
        weight: 300;
    }
}

p {
    @extend %base;
    color: aqua;
}

.btn{
    @extend %base;
}